QoS-guaranteed video stream method and system, and transmitting server

ABSTRACT

Provided is a quality-of-service (QoS)-guaranteed video stream method. The QoS-guaranteed video stream method includes transmitting, by a transmitting server, a video stream including different video stream data for a plurality of respective layers, to a relay server, receiving, by the transmitting server, first section network state information which is information about a network state between the relay server and the transmitting server, from the relay server, receiving, by the transmitting server, second section network state information which is information about a network state between the plurality of respective user terminals and the transmitting server, and adjusting, by the transmitting server, qualities of video streams which are transmitted to the plurality of respective user terminals through the relay server by using network state information of the first section and network state information of the second section.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2014-0100546 filed on Aug. 5, 2014 in the Korean IntellectualProperty Office, and all the benefits accruing therefrom under 35 U.S.C.119, the contents of which in its entirety are herein incorporated byreference.

BACKGROUND

1. Field of the Invention

The present invention relates to a QoS-guaranteed video stream methodand system, and a transmitting server, and more particularly, to aQoS-guaranteed video stream method and system, and a transmitting servercapable of guaranteeing QoS in a scheme of providing a video stream byusing a plurality of layers.

2. Description of the Related Art

Along with development of a mobile device and a mobile network, a mobilevoice over internet protocol (VoIP) service, through which images areexchanged between a plurality of users in real time by using a mobiledevice, is getting popular. Further, a real time streaming service suchas a professional baseball game live broadcast in a mobile device isalso getting popular.

A scalable video codec (SVC) may be user to transmit a video stream to aplurality of users. A scalable video codec such as H.264 SVC may formone video stream with a plurality of layers so as to be transmitted.

According to the technology of providing a video stream by using a SVC,a transmitting server transmits one video stream to a relay server, anda plurality of user terminals connect to the relay server and receivethe video stream.

The technology of providing a video stream by using a SVC according to aconventional art transmits a video stream which is optimized in anetwork situation between a transmitting server and a relay server.Hence, the image quality of the layer received by the user terminal mayprovide only a scheme of selecting one layer from among video streamshaving the image quality for each defined layer based on the networksituation between the transmitting server and the relay server. That is,there is a limit that the network state between the user terminal andthe relay server does not affect the quality of the video stream whichis transmitted by the transmitting server.

SUMMARY

The present invention provides a QoS-guaranteed video stream method andsystem, and a transmitting server capable of adjusting the quality ofthe video which is provided to each user terminal for each layer inconsideration of both the network state between the transmitting serverand the relay server and the network state between respective userterminals.

The present invention further provides a QoS-guaranteed video streammethod and system, and a transmitting server capable of providing avideo stream while guaranteeing the QoS when providing a video stream byusing a plurality of layers such as a scalable video codec (SVC).

According to an aspect of the present invention, there is provided aquality-of-service (QoS)-guaranteed video stream method comprising:transmitting, by a transmitting server, a video stream includingdifferent video stream data for a plurality of respective layers, to arelay server; receiving, by the transmitting server, first sectionnetwork state information which is information about a network statebetween the relay server and the transmitting server, from the relayserver; receiving, by the transmitting server, second section networkstate information which is information about a network state between theplurality of respective user terminals and the transmitting server; andadjusting, by the transmitting server, qualities of video streams whichare transmitted to the plurality of respective user terminals throughthe relay server by using network state information of the first sectionand network state information of the second section.

According to another aspect of the present invention, there is provideda transmitting server comprising: a transmitting unit which transmits avideo stream including different video stream data to a relay server fora plurality of respective layers; a first receiving unit which receivesfirst section network state information, which is information about thenetwork state between the relay server and the transmitting server, fromthe relay server; a second receiving unit which receives second sectionnetwork state information, which is information about the network statebetween the plurality of respective user terminals and the transmittingserver; and an adjustment unit which adjusts qualities of video streams,which are transmitted to the plurality of respective user terminalsthrough the relay server by using the first section network stateinformation and the second section network state information, for therespective layers.

According to another aspect of the present invention, there is provideda quality-of-server (QoS)-guaranteed video stream system comprising: atransmitting server which transmits video streams including differentvideo stream data to a relay server for a plurality of respectivelayers; a relay server which transmits first section network stateinformation, which is information on the network state with thetransmitting server, to the transmitting server; and a plurality of userterminals which transmits second section network state information,which is information on the network state with the transmitting server,to the transmitting server through the relay server, wherein thetransmitting server adjusts qualities of video streams which aretransmitted to the plurality of respective user terminals through therelay server by using the first section network state information andthe second section network state information.

According to another aspect of the present invention, there is provideda quality-of-service (QoS)-guaranteed video stream method comprising:transmitting, by a transmitting server, a video stream includingdifferent video stream data for a plurality of respective layers, to arelay server; receiving, by the transmitting server, first sectionnetwork state information which is information about a network statebetween the relay server and the transmitting server, from the relayserver; receiving, by the transmitting server, second section networkstate information which is information about a network state between theplurality of respective user terminals and the transmitting server; andadjusting, by the transmitting server, qualities of video streams whichare transmitted to the plurality of respective user terminals throughthe relay server by using network state information of the first sectionand network state information of the second section.

According to another aspect of the present invention, there is provideda quality-of-service (QoS)-guaranteed video stream method comprising:transmitting, by a transmitting terminal, a video stream includingdifferent video stream data for a plurality of respective layers, to arelay server; receiving, by the transmitting terminal, first sectionnetwork state information which is information about a network statebetween the relay server and the transmitting server, from the relayserver; receiving, by the transmitting terminal, second section networkstate information which is information about a network state between theplurality of respective user terminals and the transmitting server; andadjusting, by the transmitting terminal, qualities of video streamswhich are transmitted to the plurality of respective user terminalsthrough the relay server by using network state information of the firstsection and network state information of the second section.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings in which:

FIG. 1 is a block diagram about a QoS-guaranteed video stream systemaccording to an embodiment of the present invention;

FIGS. 2 and 3 illustrate a method of providing a video stream ofdifferent qualities for respective user terminals by using a pluralityof layers by a scalable video codec technology;

FIG. 4 illustrates an example about a video stream which is received byeach user terminal;

FIG. 5 illustrates network state information of a first section;

FIGS. 6A and 6B illustrate network state information of a secondsection;

FIG. 7 is a signal flowchart indicating a QoS-guaranteed video streammethod according to another embodiment of the present invention;

FIGS. 8 to 10 illustrate an example of adjusting the quality of thevideo stream for respective layers by a transmitting server; and

FIG. 11 is a block diagram illustrating a transmitting server accordingto further another embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the attached drawings. The advantages andfeatures of the present invention and methods for achieving them willbecome clear by referring to the attached drawings and the embodimentswhich are described later in detail. However, the present invention isnot limited to the embodiments which are disclosed below, but thepresent invention may be implemented in various other forms. Theembodiments are provided to complete the disclosure of the presentinvention and to let one of ordinary skill in the art clearly understandthe scope of the invention, and the present invention is defined by thescope of claims. The same reference numerals refer to the samecomponents throughout the specification.

Unless defined otherwise, all the terms used in the presentspecification (including technical and scientific terms) may be used asmeanings which may be commonly understood to one of ordinary skill inthe art. Further, the terms which are defined in a generally useddictionary are not ideally or excessively understood unless speciallydefined.

In the present specification, a singular form also includes a pluralform unless specially mentioned.

The terms “comprise” and/or “comprising” used in the specification donot exclude the existence or addition of one or more components, steps,operations, and/or devices other than the mentioned components, steps,operations, and/or devices.

FIG. 1 is a block diagram about a QoS-guaranteed video stream systemaccording to an embodiment of the present invention.

Referring to FIG. 1, a QoS-guaranteed video stream system according toan embodiment of the present invention may include a transmitting server100, a relay server 200, and a plurality of user terminals 300.

The transmitting server 100 transmits a video stream to the relay server200.

The transmitting server 200 transmits a video stream, which istransmitted from the transmitting server 100, to the plurality of userterminals 300.

The QoS-guaranteed video stream system according to an embodiment of thepresent invention may be used in a service which provides a video streamto a user terminal by using a wired or wireless network.

The QoS-guaranteed video stream system according to an embodiment of thepresent invention may be applied even when there is one user terminaland may also be effectively applied when there are a plurality of userterminals.

In particular, the QoS-guaranteed video stream system according to anembodiment of the present invention may be effectively used in theservice which provides a video stream by using a plurality of layers 10such as a scalable video codec (SVC).

FIGS. 2 and 3 illustrate a method of providing video streams ofdifferent qualities for respective user terminals by using a pluralityof layers 10 by using a SVC technology.

The plurality of layers may be 2 to 8 or more layers, but FIGS. 2 and 3illustrate a case where there are a first layer 11, a second layer 12, athird layer 13, and a fourth layer 14.

The transmitting server 100 transmits a video stream to the userterminal via the relay server 200 by using the first layer 11 to thefourth layer 14.

The user terminal may receive first video stream data 21 by using thefirst layer 11. Further, the user terminal may receive first imagestream data 21 and second video stream data 22 by using the first layer11 and the second layer 12.

Further, the user terminal may receive first video stream data 21,second video stream data 22, and third video stream data 23. Further,the user terminal may receive first video stream data 21, second videostream data 22, third video stream data 23, and fourth video stream data24 by using the first layer 11, the second layer 12, the third layer 13,and the fourth layer 14.

Referring to FIG. 3, the quality of the video received when the userterminal receives only the first video stream data 21 by using the firstlayer 11 may be less than the quality of the video which is providedwhen the user terminal receives the first video stream data 21 and thesecond video stream data 22 by using the first layer 11 and the secondlayer 22.

Further, the quality of the video received when the first video streamdata 21 and the second video stream data 22 are received by using thefirst layer 11 and the second layer 12 may be less than the quality ofthe video received when the first video stream data 21, the second videostream data 22, and the third video stream data 23 are received by usingthe first layer 11, the second layer 12, and the third layer 13.

Further, the quality of the video received when the first stream data21, the second video stream data 22, and the third video stream data 23are received by using the first layer 11, the second layer 12, and thethird layer 13 may be less than the quality of the video received whenthe first image stream data 21, the second video stream data 22, thethird video stream data 23, and the fourth video stream data 24 arereceived by using the first layer 11, the second layer 12, the thirdlayer 13, and the fourth layer 14.

That is, the user terminal may be provided the video of a higher qualitywhen more video stream data is receive by using up to the upper layersthan when receiving only the first stream data 21 by using the firstlayer 11.

Specifically, the first video stream data 21, the second video streamdata 22, the third video stream data 23, and the fourth video streamdata 24 are generated and encoded by using SVC technology. That is, thesum of the first video stream data 21, the second video stream data 22,the third video stream data 23, and the fourth video stream data 24 maybe the same as the data which is generated by encoding the video withthe best resolution by using the SVC technology. The first video streamdata 21 may replayed only with the first video stream data 21, but theimage quality such as the resolution is low, and as the video streamdata, which is received by using the upper layers, is added, the imagequality gets closer to the best resolution.

When it is stated in the present specification that a video stream istransmitted or received by using an upper layer, it also includestransmitting or receiving the video stream by using the lower layers ofthe upper layer.

That is, when it is stated in the present specification that thetransmitting server transmits a video stream to the first user terminal310 via the relay server 200 using the third layer 13, it means that thefirst video stream data 21 which is transmitted by using the first layer11, the second video stream data 22 which is transmitted by using thesecond layer 12, and the third video stream data 23 which is transmittedby using the third layer 13 are also included when transmitted.

As another example, if it is stated in the specification that thetransmitting server 100 transmits a video stream to the first userterminal 310 through the relay server 200 by using the fourth layer 14,it means that the first video stream data 21 which is transmitted byusing the first layer 11, the second video stream data 22 which istransmitted by using the second layer 12, the third video stream data 23which is transmitted by using the third layer 13, and the fourth videostream data 14 which is transmitted by using the fourth layer 14 arealso included when transmitted.

The QoS-guaranteed stream system according to an embodiment of thepresent invention may be more effectively applied to the video streamproviding system by using the above-described scalable video codec thanthe video stream service which is provided the video stream by selectingone of a low image quality, an intermediate image quality, and a highimage quality.

In the video streaming service in which the video stream is provided byselecting one of a low image quality, an intermediate image quality, anda high image quality, if the user selects the high image quality, thevideo stream data of a high image quality are provided, but when thenetwork environment is poor, the video may frequently stop.

However, in the QoS-guaranteed stream system according to an embodimentof the present invention, the user does not select the image quality,and the video streaming is provided by adjusting the image quality inreal time or periodically in consideration of the network environment,and thus even if the image quality is lowered, the video rarely stops.

To this end, the QoS-guaranteed video stream system according to anembodiment of the present invention adjusts the image quality which isprovided for respective user terminal in overall consideration of theinformation on the network state between the transmitting server 100 andthe relay server 200 and the information on the network state betweenthe relay server 200 and respective user terminals.

Hereinafter, a method of providing a QoS-guaranteed video stream byadjusting the quality of the video which the QoS-guaranteed video streamsystem provides to respective user terminals will be described withreference to FIGS. 1 and 4 to 6.

FIG. 4 illustrates an example about a video stream which is received byeach user terminal.

Referring to FIGS. 1 and 4, the relay server 200 receives a video streamfrom the transmitting server 100. The relay server 200 transmits a videostream to each user terminal by using a specific layer according to thesetting in the transmitting server 100.

A specific method of transmitting a video stream by using a specificlayer to each user terminal according to the setting in the transmittingserver 100 will be described later.

Continually referring to FIG. 4, the first user terminal 310 receives avideo stream by using the first layer 11. The second user terminal 320receives a video stream by using the second layer 12. The third userterminal 330 receives a video stream by using the third layer 13.

As described above, the second user terminal 320 receives first videostream data 21 and second video stream data 22 by using the second layer12 and replays the video by using the first video stream data 21 and thesecond video stream data 22, and thus the image quality may be betterthan when receiving the video stream by using the first layer 11.

Likewise, the third user terminal 330 receives the first video streamdata 21 to the third video stream data 23 by using the third layer 13 inorder to replay a video, and thus the image quality may better than theimage quality of the video which is replayed in the first user terminal310 and the second user terminal 320.

FIG. 5 illustrates the state information of a first section network 51.

The transmitting server 100 adjusts the image quality of the video whichis provided for respective user terminals 310, 320, and 330 in overallconsideration of the network state information between the transmittingserver 100 and the relay server 200 and the network state informationbetween the relay server 200 and respective user terminals 310, 320, and330.

Referring to FIG. 5, the network between the transmitting server 100 andthe relay server 200 is called a first section network 51. Thetransmitting server 100 transmits a video stream to the relay server200. The relay server 200 transmits the state information on the firstsection network 51 to the transmitting server 100.

That is, the transmitting server 100 receives the state information onthe first section network 51 from the relay server 200.

Specifically, the transmitting server 100 may receive state informationof the first section network 51 from the relay server 200 by using thereal time transport protocol (RTCP).

The state information of the first section network 51 may include atleast one of a packet loss, a jitter, and a delay in the first sectionnetwork.

Further, state information on the first section network 51 may includeinformation which is needed to calculate the available bandwidth forrespective user terminals 310, 320, and 330.

The available bandwidth may be calculated by various methods, andrespective methods have their own advantages and disadvantages. Aspecific method for calculating the available bandwidth may include analready known method and may be set in consideration of the networkenvironment to which the present invention is applied. For example, theavailable bandwidth may be calculated by using at least one of thepacket loss, the jitter, and the delay information.

The relay server 200 may transmit the state information of the firstsection network 51 to the transmitting server 100 in real time,periodically, or aperiodically. The relay server 200 may usetransmitting state information of the first section network 51 to thetransmitting server 100 periodically in consideration of the networkchangeability and the load of the data transmission and reception anddata process, etc. as the basic setting.

FIGS. 6A and 6B illustrate state information of the second sectionnetwork.

Referring to FIG. 6A, the second section network 61 refers to a networkbetween the relay server 200 and the user terminal.

The relay server 200 transmits a video stream received from thetransmitting server 100 to respective user terminals 310, 320, and 330,and receives state information of the second section network 61 fromrespective user terminals.

For example, the relay server 200 receives network state informationbetween the relay server 200 and the first user terminal 310 from thefirst user terminal 310.

The relay server 200 receives the network state information between therelay server 200 and the second user terminal 320 from the second userterminal 320.

The relay server 200 receives network state information between therelay server 200 and the third user terminal 330 from the third userterminal 330.

The network state information sets, which are received from the firstuser terminal 310, the second user terminal 320, and the third userterminal 330, which are respective user terminals, by the relay server200, become the state information of the second section network 61.

The relay server 200 transmits the state information of the secondsection network 61 including the network state information, which isreceived from respective user terminals, to the transmitting server 100.

The relay serve 200 may receive network state information in real time,periodically, or aperiodically from respective user terminals 310, 320,and 330. However, when the relay server 200 collects the network stateinformation received from respective user terminals 310, 320, and 330,and transmits the collected network state information to thetransmitting server 100, the relay server 200 needs to perform aprocedure for collecting the state of the second section network 61.

Hence, the case where the relay server bypasses the state information ofthe second section to the transmitting server 100 may be more easilyimplemented.

The relay server 200 may transmit state information on the secondsection network 61, which is received from respective user terminals310, 320, and 330, to the transmitting server 100 in real time,periodically, or aperiodically.

Respective user terminals 310, 320, and 330 may transmit network stateinformation between the relay server 200 and respective user terminals310, 320, and 330 to the relay server 200 by using a real time transportprotocol (RTCP).

The relay server 200 may also transmit the state information on thesecond section network 61 to the transmitting server 100 by using RTCP.

However, the relay server 200 may transmit the data, which istransmitted by the transmitting server 100, in a bypassing form withouta particular process. Hence, the network state information, which may bemeasured in respective user terminals 310, 320, and 330, maysubstantially become the network state information between thetransmitting server 100 and the user terminal itself which measures thenetwork state information.

Referring to FIG. 6B, the second section network 61 may substantiallybecome a network between the transmitting server 100 and respective userterminals. However, when the relay server processes the data, which istransmitted from the transmitting server 100, without transmitting thedata in a bypassing form, the second section network 61 may be like asshown in FIG. 6A.

In FIGS. 6A and 6B, the state information of the second section network61 includes network state information which each user terminal transmitsto the transmitting server through the relay server. That is, in FIG.6B, the relay server 200 transmits the network state information betweenthe first user terminal 310 and the transmitting server 100 which isreceived from the first user terminal, from among the state informationon the second section network 61, to the transmitting server 100 througha bypass. Further, the relay server 200 transmits the network stateinformation between the second user terminal 320 and the transmittingserver 100, which is received from the second user terminal 320, fromamong the state information on the second section network 61, to thetransmitting server 100 through a bypass. Further, the relay server 200transmits the network state information between the third user terminal330 and the transmitting server 100, which is received from the thirduser terminal 330, from among the second section network 61, to thetransmitting server 100 through a bypass.

The state information on the second section network 61 may contain atleast one of the packet loss, the jitter, and the delay in the secondsection network 61. That is, in FIG. 6, the state information on thesecond section network 61 includes information on at least one of thepacket loss, the jitter, and the delay in the network between the relayserver 200 and the first user terminal 310. Further, the stateinformation on the second section network 61 includes information on atleast one of the packet loss, the jitter, and the delay in the networkbetween the relay server 200 and the second user terminal 320. Further,the state information on the second section network 61 includesinformation on at least one of the packet loss, the jitter, and thedelay in the network between the relay server 200 and the third userterminal 330.

The state information on the second section network 61 may containinformation which is needed to calculate the available bandwidth forrespective user terminals 310, 320, and 330.

As described above, there may be various methods of calculating theavailable bandwidth and an already known method may also be used.Further, the method may also be set in consideration of the networkenvironment to which the present invention is applied. For example, theavailable bandwidth may be calculated the jitter information in thefirst section network 51 and the jitter information in the secondsection network 61.

The state information of the second section network 61 may include theidentification information of the user terminal which has transmittedthe network state information to the relay server 200. The transmittingserver 100 may identify the user terminal which has transmitted specificnetwork state information by using identification information.

Identification information may be, for example, information which hasused a unique key. As another example, the identification informationmay be information which uses the network address such as an IP addressor port at which a video stream is received.

The transmitting server 100 adjusts the quality of the image which isreceived by respective user terminals by using the state information onthe first section network 51 and the state information on the secondsection network 61.

The transmitting server 100 may adjust the quality of the video streamswhich are transmitted for respective layers in order to adjust thequalities of the videos which are received by respective user terminals.

The QoS-guaranteed video stream system and the transmitting server 100according to an embodiment of the present invention will be described inmore detail with reference to the QoS-guaranteed video stream systemaccording to another embodiment of the present invention.

Hereinafter, a QoS-guaranteed video stream method according to anotherembodiment of the present invention will be described with reference toFIGS. 7 to 10.

The points explained in the QoS-guaranteed video stream method and thetransmitting server 100 according to another embodiment of the presentinvention may be applied to the QoS-guaranteed video stream method andthe transmitting server 100 according to the first embodiment of thepresent invention. Further, the points explained in the QoS-guaranteedvideo stream method and the transmitting server 100 according to thefirst embodiment of the present invention may also be applied to theQoS-guaranteed video stream method and the transmitting server 100according to other embodiments of the present invention.

FIG. 7 is a signal flowchart indicating a QoS-guaranteed video streammethod according to another embodiment of the present invention.

Referring to FIG. 7, the transmitting server 100 transmits a videostream to the relay server 200 (S705).

The transmitting server 100 receives the state information on the firstsection network 51, which is the network state information between therelay server 200 and the transmitting server 100, from the relay server200 (S710).

There may be a plurality of user terminals. FIG. 7 illustrates a casewhere there are three user terminals.

The user terminal may receive a video stream, which is transmitted bythe transmitting server 100, through the relay server 200.

The first user terminal 310 may receive a video stream by using thefirst layer 11 (S715). That is, the first user terminal 310 may receivea first video stream by using the first layer 11.

The second user terminal 320 may receive a video stream by using thesecond layer 12 (S720). That is, the second user terminal 320 mayreceive first video stream by using the first layer 11 and may receivesecond video stream data 22 by using the second layer 12.

The user terminal 330 may receive a video stream by using the thirdlayer 13 (S720). That is, the third user terminal 330 may receive thefirst video stream data 21 by using the first layer 11, may receivesecond video stream data 22 by using the second layer 12, and mayreceive third video stream data 23 by using the third layer 13.

The quality of the video, which is replayed by the second user terminal320 and the third user terminal 330, is higher than the quality of thevideo which is replayed by the first user terminal 310. The quality ofthe video, which is replayed by the third user terminal 330, is higherthan the quality of the video which is replayed by the second userterminal 320.

The first user terminal 310 transmits network state information betweenthe first user terminal 310 and the relay server 200 to the relay server200 (S730).

The second user terminal 320 transmits the network state informationbetween the second user terminal 320 and the relay server 200 to therelay server 200 (S735).

The third user terminal 330 transmits the network state informationbetween the third user terminal 300 and the relay server 200 to therelay server 200 (S740).

The relay server 200 transmits state information on the second sectionnetwork 61, which is received from respective user terminals 310, 320,and 330 in operations S730, S735, and S740, to the transmitting server100 (S745).

Specifically, the relay server 200 may collect the state information onthe second section network 61 which is received from respective userterminals 310, 320, and 330 and periodically transmit the collectedstate information to the transmitting server 100.

Preferably, if the relay server 200 receives the state information onthe second section network 61 from respective user terminals 310, 320,and 330, the relay server 200 may promptly transmit the received stateinformation to the transmitting server 100 through a bypass withoutperforming a process such as the collection.

The transmitting server 100 may adjust the quality of the video streamfor respective layers by using the state information of the firstsection network 51 and the state information of the second sectionnetwork 61 so that respective user terminals 310, 320, and 330 may beprovided a video stream of a quality which is optimized in the networksituation while guaranteeing QoS (S750).

The transmitting server 100 may periodically (or aperiodically) receivethe state information of the first section network 51 and the stateinformation of the second section network 61. The transmitting server100 may adjust the quality of a video stream for respective layers byusing the state information of the first section network 51 and thestate information of the second section network 61 which areperiodically received so that respective user terminals 310, 320, and330 may be provided a QoS-guaranteed video stream.

Specifically, the transmitting server 100 may calculate the availablebandwidth for respective user terminals 310, 320, and 330 by using thestate information of the first section network 51 and the stateinformation of the second section network 61 and adjust the quality ofthe video stream for respective layers by using the calculated availablebandwidth. For example, when the available bandwidth of a certain userterminal is greater than a currently used bandwidth, the user terminalmay be provided a video of a higher quality, which shows that thetransmitting server 100 may provide a video stream of a higher quality.

Further, the transmitting server 100 may adjust the quality of the videostream for respective layers by using the packet loss, jitter, and delayinformation which are included in the state information of the firstsection network 51 and the state information of the section network 61.For example, when the packet loss, jitter, or delay information of acertain user terminal is high, it is understood that the current networksituation of the user terminal is poor, and thus the transmitting server100 may provide video stream data of a lower quality so that the videodoes not stop.

FIGS. 8 to 10 illustrate an example where the transmitting server 100adjusts the quality of a video stream for respective layers.

Specifically, FIGS. 8 to 10 illustrate an example of adjusting thequality of a video stream for respective layers by calculating availablebandwidths for respective user terminals and adjusting the quality ofvideo streams for respective layers by using the calculated availablebandwidths.

Referring to FIG. 8, a plurality of user terminals 300 include a firstuser terminal 410 to a ninth user terminal 390.

The transmitting server 100 may receive state information of the firstnetwork state 51 and the state information of the second section network61 and calculate respective available bandwidths of the first userterminal 310 to the ninth user terminal 390 by using the receivednetwork state information.

The transmitting server 100 may understand the information on thecurrently used layers for respective user terminals and bandwidths whichare used by the current layers by using the received state informationof the first section network 51 and state information of the sectionnetwork 61. However, the currently used layers for respective userterminals and the bandwidths used by current layers are adjusted anddetermined by the transmitting server 100, and thus they are notnecessarily understood by using the state information of the firstsection network 51 and the state information of the second sectionnetwork 61.

Continually referring to FIG. 8, the first user terminal, the seconduser terminal 320, the third user terminal 330, and the eighth userterminal 380 are provided a video stream by using the third layer 13.

The fact that the user terminal is provided a video stream by using thethird layer 13 means that the first video stream data 21 and the secondvideo stream data 22, which use the first layer 11 and the second layer12, are also received, and thus the largest amount of bandwidths areused and the video of the highest quality may be provided.

The fourth user terminal 340, the fifth user terminal 350, and the sixthuser terminal 360 are provided a video stream by using the second layer12.

The seventh user terminal 370 and the ninth user terminal 390 areprovided a video stream by using the first layer 11.

The values, which are generated as the transmitting server 100calculates available bandwidths of from the first user terminal 310 tothe ninth user terminal 390 by using the information on the firstsection network 51 and the information on the second section network 61.

The transmitting server 100 may adjust the image quality such as thetransmission rate of the video stream which is provided by using aspecific layer on the basis of the user terminal having the lowestavailable bandwidth from among user terminals which receive a videostream by using the specific layer.

FIG. 9 illustrates an example of adjusting a video quality forrespective layers by the transmitting server 100.

That is, referring to FIG. 8, all user terminals, which receive a videostream by using the third layer 13, have sufficient availablebandwidths. Further, it may be understood that the eighth user terminal380 is the user terminal having the lowest available bandwidth fromamong user terminals which receive a video stream by using the thirdlayer 13.

Hence, referring to FIG. 9, the transmitting server 100 may adjust thetransmission rate of the video stream which is provided by using thethird layer on the basis of the available bandwidth of the eighth userterminal 380 so that the user terminals which use the third layer 13 mayreceive the video of a higher quality.

Referring to FIG. 8, the available bandwidth of the fourth user terminal340, from among the user terminals which receive a video stream by usingthe second layer 12, is not enough to receive a video stream by usingthe current second layer 12.

Hence, referring to FIG. 9, the transmitting server 100 may lower thetransmission rate of the video stream which is provided by using thesecond layer 12 on the basis of the fourth user terminal 340 having thelowest available bandwidth from among user terminals which receive avideo stream by using the second layer 12, so that all user terminalswhich use the second layer 12 may receive a video stream in theQoS-guaranteed environment.

Referring to FIG. 8, from among the user terminals which receive a videostream by using the first layer 11, the available bandwidth of the ninthuser terminal 390 is lowest. Hence, referring to FIG. 9, thetransmitting server 100 may lower the transmission rate of the videostream which is provided by using the first layer 11 on the basis of theninth user terminal 390 so that the video stream may be received in theQoS-guaranteed environment.

FIG. 10 illustrates another example of adjusting the image quality forrespective layers by the transmitting server 100.

The transmitting server 100 adjusts the image quality such as thetransmission rate of the video stream which is provided by using aspecific layer on the basis of a user terminal having the lowestavailable bandwidth from among user terminals which receive a videostream by using the specific layer. However, if the user terminal havingthe lowest available bandwidth is a predetermined level or less, thelayer used by the user terminal having the lowest bandwidth is changedto the lower layer. Further, the transmitting server 100 may adjust theimage quality such as the transmission rate of the video stream which isprovided by using the specific layer on the basis of the user terminalhaving the second lowest available bandwidth.

When the user terminal having the second lowest available bandwidth is apredetermined level or less, the transmitting server 100 may change thelayer, which is used by the user terminal having the second lowestavailable bandwidth, to a lower layer. Further, the transmitting server100 may adjust the image quality such as the transmission rate of avideo stream which is provided by using the specific layer on the basisof the available bandwidth of the user terminal having the lowestavailable bandwidth from among the remaining user terminals.

By such a scheme, the phenomenon that the overall quality is lowered onthe basis of the user terminal of which network state is poor or hasbecome poor may be prevented.

More specifically, referring to FIGS. 8 to 10, when the transmissionrate of a video stream, which is provided by using the second layer 12on the basis of the fourth user terminal 340 which uses the second layer12, is lowered, QoS may be guaranteed, but the fifth user terminal 350and the sixth user terminal 360 cannot sufficiently use the bandwidthand may be provided the video of a low quality. Hence, the transmittingserver 100 may change the layer used by the fourth user terminal 340 tothe first layer 11. Further, the transmitting server 100 may enhance thetransmission rate of the video stream which is provided by using thesecond layer 12 on the basis of the sixth user.

Similarly to what has been described with reference to FIG. 10, whenthere is a user terminal of which the available bandwidth is apredetermined level or higher, the transmitting server 100 may be set tobe provided the video of a high quality by changing the layer used bythe user terminal to an upper layer.

The predetermined level may be set in consideration of the bandwidthwhich is used in the video stream for respective layers and the gap ofthe bandwidth which is used in the video stream for respective layers.Further, the predetermined level may be flexibly changed as thebandwidth, which is used in the video stream, is changed for respectivelayers.

The transmitting server 100 does not necessarily need to adjust thequality of the video stream for respective layers by calculating theavailable bandwidth. The transmitting server 100 may set the criticalvalue for respective indicators which reveal the network state such asthe packet loss, the jitter, and the delay information, and adjust theimage quality so that the network state for the video stream may bemaintained lower than the critical value.

The adjusting of the image quality includes adjusting the transmissionrate.

Further, the transmitting server 100 may set a specific function byusing one of indicators such as the packet loss, the jitter, and thedelay, not the available bandwidth, and may adjust the image quality forrespective layers by adjusting the transmission rate, etc. forrespective layers in order to make the value of the predeterminedspecific function to be lower than a preset critical value or to beminimized. The specific function may be differently set or changedaccording to the network situation or type, etc.

When the transmitting server 100 set a specific function and adjusts theimage quality for respective layers by using the predetermined specificfunction, the points of calculating the available bandwidth andadjusting the image quality for respective layers by using thecalculated bandwidth which has been described with reference to FIGS. 7to 9 may be used in the same or similar manner.

As another example of adjusting the image quality for respective layersby the transmitting server 100, in a situation as in FIG. 8, if aspecific user terminal is an important terminal having a higher prioritysuch as a terminal used for a CEO conference, the QoS may be guaranteedon the basis of the important terminal so that the highest quality videostream may be provided to the terminal and thereby the image quality maybe adjusted for respective layers.

The transmitting server 100 may the information of image qualityadjustment for respective layers to respective user terminals throughthe relay server 200.

For example, the transmitting server 100 may include receiverinformation of each packet in the each packet when transmitting eachpacket. Specifically, it is assumed that there is user terminal A whichreceives video stream data by using both the first layer 11 to the thirdlayer 13, user terminal B which receives video stream data by using thefirst layer 11 and the second layer 12, and user terminal C whichreceives video stream data by using the first layer 11.

Under the above consumption, the transmitting server 100 includes userterminals A, B, and C as the receiver information in the packet headerof the first video stream data 21 which uses the first layer 11 fromamong the video stream data of which image quality has been adjusted.Further, the transmitting server 100 includes user terminals A and B asthe receiver information in the packet header of the second video streamdata 22 which uses the second layer 12 from among video stream data ofwhich the image quality has been adjusted. Further, the transmittingserver 100 includes terminal A as the receiver information in the packetheader of the third video stream data 23 which uses the third layer 13from among video stream data of which the image quality has beenadjusted. Likewise, after including the receiver information in thepacket header, the video stream may be transmitted to the relay server200.

As another method, the transmitting server 100 includes a value whichallows judgment on the layer information of the packet in the packetheader of the video stream data. Further, the transmitting server 100may transmit a separate message to the relay server 200 in order toreveal the information that user terminal A receives video stream databy using all of the first layer 11 to the third layer 13, user terminalB receives video stream data by using the first layer 11 and the secondlayer 12, and user terminal C receives video stream data by using thefirst layer 11.

The relay server 200 may determine the layer of the packet of thereceived video stream data, and thus an appropriate layer may be relayedto respective user terminals according to the information included in aseparate message.

Further, the transmitting server 100 may not separately include thevalue for determining the layer information in the packet, and the relayserver 200 may determine the layer information of the packet byanalyzing the video stream data.

FIG. 11 is a block diagram illustrating a transmitting server 100according to further another embodiment of the present invention.

Referring to FIG. 11, the transmitting server 100 may include atransmitting unit 110, a first receiving unit 120, a second receivingunit 130, and an adjustment unit 140. Each of the transmitting unit, thefirst receiving unit, the second receiving unit, and the adjustment unitare implemented via a CPU or hardware processor.

The transmitting unit 110 transmits a video stream to the relay server200.

The transmitting unit 110 transmits a video stream, of which the imagequality has been adjusted for respective layers in the adjustment unit,to the relay server 200.

The first receiving unit 120 may receive network information of thefirst section. The second receiving unit 130 may receive networkinformation of the second section.

Both the information on the first section network 51 and the informationon the second section network 61 may be received from the relay server200, and thus the first receiving unit 120 and the second receiving unit130 may be processed by one receiving unit.

The adjustment unit 140 may guarantee QoS by adjusting the image qualityby adjusting the transmission rate for respective layers by using theinformation on the first section network 51 and the information on thesecond section network 61.

The transmitting server 100 according to an embodiment of the presentinvention, which has been described with reference to FIGS. 1 to 11, isnot necessarily a server, but it may also be a terminal.

For example, in the peer to peer (P2P) network connection, the role ofthe transmitting server 100 may be performed by a specific terminal.

Respective components of FIG. 11 may be software, or hardware such asfield-programmable gate array (FPGA) or application-specific integratedcircuit (ASIC). However, the components are not limited to software orhardware, but the components may be configured to be in an addressablestorage medium or may be configured to execute one or more processors.The function, which is provided in the components, may be implemented bymore segmented components, and may be implemented as one component whichperforms a certain function by combining a plurality of components.

According to some embodiments of the present invention, a video streammay be provided while guaranteeing the QoS when providing a video streamby using a plurality of layers such as a scalable video codec (SVC).

According to some embodiments of the present invention, a video streamof a quality optimized in a network situation may be provided to eachuser terminal by adjusting the image quality in consideration of theoverall network state between the transmitting server, the relay server,and respective user terminals.

The embodiments of the present invention have been described above withreference to the attached drawings, but it may be understood by one ofordinary skill in the art that the present invention may be executed inother specific forms without changing the technical idea and essentialfeatures. Hence, it should be understood that the above-describedembodiments are merely examples and do not limit the scope of thepresent invention.

What is claimed is:
 1. A quality-of-service (QoS)-facilitating videostreaming method comprising: transmitting, by a transmitting server, toa relay server, a video stream including a plurality of video datastreams, a first video data stream of the plurality of video datastreams corresponding to a first layer of a plurality of respectivelayers of the video stream, and a second video data stream of theplurality of video data streams corresponding to a second layer of aplurality of respective layers of the video stream; receiving, by thetransmitting server, from the relay server, first section network stateinformation which is information about a network state between the relayserver and the transmitting server; receiving, by the transmittingserver, from the relay server, second section network state informationwhich is information about a network state between a plurality ofrespective user terminals and the transmitting server; and adjusting, bythe transmitting server, by using the first section network stateinformation and the second section network state information, atransmission rate of the first video data stream, wherein every data ofthe first video data stream is transmitted to first corresponding userterminals of the plurality of respective user terminals through therelay server at the adjusted transmission rate, and every data of thesecond video data stream is transmitted to second corresponding userterminals of the plurality of user terminals at the originaltransmission rate of the second video data stream through the relayserver.
 2. The QoS-facilitating video streaming method of claim 1,wherein the first section network state information comprisesinformation for calculating available bandwidths for the respective userterminals.
 3. The QoS-facilitating video streaming method of claim 1,wherein the first section network state information comprises at leastone from among a packet loss, a jitter, and a delay.
 4. TheQoS-facilitating video streaming method of claim 1, wherein thereceiving of the second section network state information comprisesreceiving a plurality of pieces of second section network stateinformation through the relay server, thereby forming the second sectionnetwork state information, the plurality of pieces of second sectionnetwork state information having been respectively transmitted by theplurality of respective user terminals.
 5. The QoS-facilitating videostreaming method of claim 1, wherein the transmitting of the videostream to the relay server comprises transmitting, by the transmittingserver, an image stream which is generated to include the plurality ofvideo data streams for the plurality of respective layers by using ascalable video codec (SVC) technology.
 6. The QoS-facilitating videostreaming method of claim 1, wherein the second section network stateinformation comprises information for calculating available bandwidthsfor the respective user terminals, and identification information of auser terminal which has transmitted network information included in thesecond section network state information.
 7. The QoS-facilitating videostreaming method of claim 1, wherein the second section network stateinformation comprises at least one from among a packet loss, a jitter,and a delay, and further includes identification information of a userterminal which has transmitted network information which is included inthe second network state information.
 8. The QoS-facilitating videostreaming method of claim 1, wherein the plurality of respective layerscomprises the first layer and a second layer, wherein the first layercorresponds to a first video stream of the plurality of respective videostreams, and the second layer corresponds to a second video stream ofthe plurality of respective video streams; and wherein the adjusting ofqualities of the plurality of respective video streams for the pluralityof respective layers further comprises: adjusting a quality of thesecond video stream which is transmitted by using the second layer basedon an available bandwidth of a user terminal having the lowest availablebandwidth from among user terminals which receive the video stream byusing the second layer.
 9. The QoS-facilitating video streaming methodof claim 1, wherein the adjusting of the qualities of the plurality ofrespective video streams comprises: changing a video stream, which istransmitted to a user terminal having an available bandwidth of apredetermined reference bandwidth or less from among user terminalswhich receive a video stream, by using a second layer corresponding to auser terminal having the lowest available bandwidth.
 10. TheQoS-facilitating video streaming method of claim 9, wherein theadjusting of the qualities of the plurality of respective video streamsfor the plurality of respective layers further comprises: adjusting aquality of a video stream which is transmitted by using the second layerbased on an available bandwidth of a user terminal from among userterminals which receive the video stream by using the second layer, theuser terminal having the lowest available bandwidth without having anavailable bandwidth of the predetermined reference bandwidth or less.11. The QoS-facilitating video streaming method of claim 9, wherein theadjusting the qualities of the video streams further comprises:adjusting a quality of a video stream which is transmitted by using thesecond layer based on an available bandwidth of a predeterminedimportant terminal when the predetermined important terminal is includedin the user terminals having an available bandwidth of the predeterminedreference available bandwidth or less.
 12. The QoS-facilitating videostreaming method of claim 1, wherein the first section network stateinformation and the second section network state information include atleast one from among a packet loss, a jitter, and a delay, wherein theplurality of respective layers correspond to the plurality of respectivevideo streams; and wherein the adjusting of the qualities of theplurality of respective video streams for the respective layerscomprises: adjusting the qualities of the plurality of respective videostreams for the plurality of respective layers based on a change of anumerical value of at least one from among the packet loss, the jitter,and the delay.
 13. A transmitting server comprising: a transmitting unitconfigured to transmit, to a relay server, a video stream including aplurality of video data streams, a first video data stream of theplurality of video data streams corresponding to a first layer of aplurality of respective layers of the video stream, and a second videodata stream of the plurality of video data streams corresponding to asecond layer of a plurality of respective layers of the video stream; afirst receiving unit configured to receive, from the relay server, firstsection network state information, which is information about thenetwork state between the relay server and the transmitting server; asecond receiving unit configured to receive, from the relay server,second section network state information, which is information about thenetwork state between a plurality of respective user terminals and thetransmitting server; and an adjustment unit configured to adjust atransmission rate of the first video data stream by using the firstsection network state information and the second section network stateinformation; wherein each of the transmitting unit, the first receivingunit, the second receiving unit, and the adjustment unit are implementedvia at least one central processing unit or at least one hardwareprocessor, and every data of the first video data stream is transmittedto first corresponding user terminals of the plurality of respectiveuser terminals through the relay server at the adjusted transmissionrate, and every data of the second video data steam is transmitted tosecond corresponding user terminals of the plurality of user terminalsat the original transmission rate of the second video data streamthrough the relay server.
 14. The transmitting server of claim 13,wherein the plurality of layers comprises the first layer and a secondlayer, wherein the first layer corresponds to a first video stream ofthe plurality of respective video streams, and the second layercorresponds to a second video stream of the plurality of respectivevideo streams; and wherein the adjustment unit adjusts a quality of avideo stream which is transmitted by using the second layer based on anavailable bandwidth of a user terminal having the lowest availablebandwidth from among user terminals which receive a video stream byusing the second layer.
 15. A quality-of-service (QoS)-facilitatingvideo streaming system comprising: a transmitting server configured totransmit, to a relay server, a video stream including a plurality ofvideo data streams, a video data stream of the plurality of video datastreams corresponding to a layer of a plurality of respective layers ofthe video stream, and a second video data stream of the plurality ofvideo data streams corresponding to a second layer of a plurality ofrespective layers of the video stream; the relay server configured totransmit, to the transmitting server, first section network stateinformation and second network state information, which are informationon the network state with the transmitting server; and a user terminalof a plurality of user terminals configured to transmit, to thetransmitting server through the relay server, a piece of second sectionnetwork state information of a plurality of pieces of second sectionnetwork state information, which is information on the network statebetween the transmitting server and the user terminal, wherein thetransmitting server adjusts a transmission rate of the first video datastream by using the first section network state information and thesecond section network state information, and every data of the firstvideo data stream is transmitted to first corresponding user terminalsof the plurality of respective user terminals through the relay serverat the adjusted transmission rate, and every data of the second videodata stream is transmitted to second corresponding user terminals of theplurality of user terminals at the original transmission rate of thesecond video data stream through the relay server.
 16. Aquality-of-service (QoS)-facilitating video streaming method comprising:transmitting, by a transmitting server, to a relay server, a videostream including a plurality of video data streams, a first video datastream of the plurality of video data streams corresponding to a firstlayer of a plurality of respective layers of the video stream, and asecond video data stream of the plurality of video data streamscorresponding to a second layer of a plurality of respective layers ofthe video stream; receiving, by the transmitting server, from the relayserver, first section network state information which is informationabout a network state between the relay server and the transmittingserver; receiving, by the transmitting server, from the relay server,second section network state information which is information about anetwork state between a plurality of respective user terminals and therelay server; and adjusting, by the transmitting server, by using thefirst section network state information and the second section networkstate information, a transmission rate of the first video data stream:wherein every data of the first video data stream is transmitted tofirst corresponding user terminals of the plurality of respective userterminals through the relay server at the adjusted transmission rate,and every data of the second video data stream is transmitted to secondcorresponding user terminals of the plurality of user terminals at theoriginal transmission rate of the second video data stream through therelay server.
 17. A quality-of-service (QoS)-facilitating videostreaming method comprising: transmitting, by a transmitting terminal,to a relay server, a video stream including a plurality of video datastreams, a video data stream of the plurality of video data streamscorresponding to a first layer of a plurality of respective layers ofthe video stream, and a second video data stream of the plurality ofvideo data streams corresponding to a second layer of a plurality ofrespective layers of the video stream; receiving, by the transmittingterminal, from the relay server, first section network state informationwhich is information about a network state between the relay server andthe transmitting server; receiving, by the transmitting terminal, fromthe relay server, second section network state information which isinformation about a network state between a plurality of respective userterminals and the transmitting server; and adjusting, by thetransmitting terminal, by using the first section network stateinformation and the second section network state information, atransmission rate of the first video data stream; wherein every data ofthe first video data stream is transmitted to first corresponding userterminals of the plurality of respective user terminals through therelay server at the adjusted transmission rate, and every data of thesecond video data stream is transmitted to second corresponding userterminals of the plurality of user terminals at the originaltransmission rate of the second video data stream through the relayserver.